Cereal-pea intercrops to improve sustainability in bioethanol production

Abstract

The environmental performance of second-generation biofuels from lignocellulosic biomass, such as crop residues, is foreseen to be superior to that of first-generation biofuels such as maize bioethanol. Moreover, using a legume as an intercrop can reduce costly N fertilizers inputs and can increase the N content of the straw mixture. Therefore, we studied cereal-legume intercrops as a source of food grain and straw bioethanol. We grew field pea and four cultivars of durum wheat, triticale, oat, and barley. Crops were grown during 2 years as a sole crop, in additive intercrop with 100 % of the sole crop density for the cereal and 50 % of sole crop density for the legume, and in replacement intercrop with 50 % of the sole crop density for each crop. Tall cereal cultivars were preferred over shorter cereals for an extra production of straw. Results show that growth resources were used up to 23–26 % more efficiently in intercrop than in sole crop for grain and straw production. Tall cereal cultivars suppressed legume yields in intercrops, thus reducing potential intercrop advantages. Pea in intercrop increased straw mixture N by 54 % the first year and by 91 % the second year, versus cereal alone.